PharmAust confirms strong data from Phase 2 study of monepantel to treat canine lymphoma

PharmAust (ASX: PAA) has confirmed positive top-line data from a Phase 2 veterinary clinical study of its lead candidate monepantel (MPL) for the treatment of canine B-cell lymphoma.

The study aimed to determine a clinically-safe and efficacious dosing regimen for the oral drug on 54 canines of mixed breeds.

It was found to be safe and well-tolerated and there were no treatment-related deaths or severe adverse reactions to the drug.

PharmAust said MPL had reached an overall clinical benefit of 35% (equating to 14 out of 40 dogs) with a median time to progression (TTP) of 28 days comparing favourably to Laverdia, which was recently approved by the US Food and Drug Administration (FDA) for B-cell and T-cell lymphoma in dogs.

TTP was defined as the time from the first date of treatment to the date the dog developed clinical or radiographic signs of progressive disease or died from any cause, including euthanasia.

The company plans to use the data to open an investigational new animal drug application with the FDA’s Centre for Veterinary Medicine (CVM).

Study sites

The open-label, single-arm, dose-finding Phase 2 study was conducted at nine sites in Australia, New Zealand and the US.

It aimed to determine a clinically-safe and efficacious dose of MPL for the treatment of dogs with B-Cell Lymphoma whilst maintaining quality of life.

Each dog received a once-daily dose of the tablet in their home environment for 28 days.

Five separate cohorts received different dosing regimens of MPL before a loading dose of 100 milligrams per kilogram body weight followed by a maintenance dose of 25mg/kg was selected as the optimal dose based on efficacy and safety data.

Canine response

The canine response to MPL therapy was assessed over 28 days following the initiation of dosing.

The overall response rate (ORR) was defined as those dogs with complete response (being the elimination of all evidence of disease, and all lymph nodes) or partial response (a 30% or greater decrease in the mean sum of the longest diameter of all target lesions from baseline).

The overall clinical benefit (OCB) was defined as those dogs with complete or partial response or stability of disease.

Strong potential

PharmAust chief executive officer Dr Michael Thurn said there was strong potential for the company to achieve a “major value inflexion point” by advancing MPL through to product registration.

“The minor investment to conduct registration studies could release significant shareholder value through the receipt of conditional approval from the CVM,” he said.

“MPL has a comparable efficacy profile to Laverdia and offers significant advantages in quality of life and safety for dogs and their owners… we are confident in the potential for MPL to be commercialised for canine cancer.”

New treatment approach

PharmAust non-executive chairman Dr Roger Aston said the drug represented a new treatment approach for the management of B-cell canine lymphoma.

“MPL could potentially eliminate the need for chemotherapy and allow dogs to maintain an excellent quality of life for an extended period of time,” he said.

“Approximately 80% of dog owners decline treatment for various reasons including limited access to specialised veterinary oncologists and clinics that carry out chemotherapy and concerns over the dog’s quality of life.”